<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    // let num = 20
    // let uname = '张三'
    // document.write(num, uname)
    let uname = prompt('请输入姓名：')
    document.write(uname)

  </script>
</body>

</html>